The invention relates to a closure arrangement for a prefillable disposable syringe made of plastic having an injection needle which is tightly connected in the outlet end of the syringe body. The closure arrangement includes an outer stiff plastic cap made of hard elastic material. The plastic cap can be seated on the syringe body and encloses the injection needle. In the region of at least the needle tip, the plastic cap is provided in its interior with a sealing lining made of a soft elastic material.
The invention also relates to a closure arrangement for a prefillable disposable syringe made of plastic wherein the closure arrangement includes a connecting cone of a conical connection with the connecting cone being formed on the outlet end of the syringe body. The closure arrangement includes an elastomeric closure cap seated on the connecting cone and the closure cap is covered by an outer stiff plastic cap connected to the injection body.
Prefilled disposable syringes having an integrated injection needle must be provided with a needle cap during storage to protect the injection needle and the syringe content irrespective of whether the syringe is made of glass or of plastic. The needle cap is only removed directly in advance of the application. These disposable syringes are, inter alia, described in well known standards wherein the injection needle is called an injection cannula and the needle cap is characterized as a protective cap. These syringes are typically manufactured for medical purposes (pharmaceutical and diagnostic) but also are made for cosmetic purposes.
Needle caps for the above-mentioned disposable syringes are known in many embodiments. The so-called classical embodiments, which are the widest known, are needle caps which are made of an elastomer, preferably rubber or natural rubber. The length is selected so that the tip of the injection needle sticks into the cap tip when the cap is seated and remains tightly closed by the material of the cap. Such a needle cap is disclosed in combination with an injection needle integrated into the injection head, for example, as shown in German patent publication 2,717,830 (FIG. 6). This needle cap has, on the one hand, the advantageous characteristic that it can be simply pushed onto the syringe head and can be completely pulled off without preparatory steps because the elastic cap skirt fits snugly and sealingly against the syringe head and thereby provides a reliable microbiological seal. The cap however has, on the other hand, several disadvantageous characteristics:
(a) The needle cap can only counter mechanical effects to a limited extent because of the softness of the material. The needle cap can also be penetrated with the handling by the user which can constitute a considerable danger of injury for the user.
(b) The needle cap is pressed together when being pulled off and comes to lie tightly against the cannula surface. This leads to at least partially stripping off the silicone applied to the needle. This silicone is intended as a sliding means during the injection operation. If this slide means is not there, the injection is painful for the patient during the injection process. Furthermore, silicone particles or droplets can form which can get into the body.
(c) The automated assembly of the needle cap is difficult because a reliably controllable path limit for the push-on operation is not present so that it can easily happen that the needle is pushed on too far or not far enough onto the syringe head. Both cases are most disadvantageous because, in the first case, the needle can penetrate through the needle cap and, in the second case, a microbiological reliable seal is no longer ensured.
(d) In the seated condition, the injection needle cannot be controlled by the user or judged, for example, whether the needle is the one suitable for the intended purpose or whether the needle is bent or damaged or contaminated. For this purpose, the needle cap must be pulled off and, if required, must be pushed on again with the very substantial danger of microbiological contamination of the needle or even of the syringe content, penetrating the needle cap and/or a bending of the needle.
(e) After pulling off the needle cap, it can be simply reseated, that is, no original sealing is guaranteed.
(f) By pulling off the needle cap, an underpressure is generated at the needle tip so that the liquid filled in the syringe can easily discharge. For the user, it is necessary to remove this liquid drop which would reduce the actual applied dose and, on the other hand, the external needle surface becomes wetted with the medicine. In this way, and during injection, medicine enters the insert channel undefined and this is generally unwanted and, for some medicines, can lead to hematomas at the injection location. Such medicines are, for example, anti-coagulants (heparin, et cetera).
To counter the above disadvantages (a) to (f), German patent publication 8,906,101 discloses a needle cap consisting of a plastic cap of a relatively hard elastic material which, on the inside, is lined with a soft elastic sealing material at least in the region of the cannula tip. In this way, this soft elastic material can be selected for optimal sealing characteristics (sealing function); whereas, the hard elastic material is more suitable to counter mechanical effects (protective function).
The invention proceeds from a needle cap of this type insofar as it relates to a prefillable disposable syringe having an integrated injection needle.
In addition to plastic disposable syringes having an integrated injection needle, also such disposable syringes are known which have a connecting cone of a cone connection, a so-called Luer lock cone connection in accordance with DIN ISO 594. The connecting cone is formed on the outlet end of the syringe body. In the case of an application, a separate needle holder can be seated on this connecting cone.
The closure arrangement for this syringe type typically comprises an elastomeric closure cap which is covered by an external stiff plastic cap made of hard elastic material. The closure cap, a so-called tip cap, is seated on the connecting cone.
It is from this kind of cap that the invention proceeds insofar as it relates to an injection body without a needle. This kind of closure arrangement is disclosed, for example, in European patent publication 0,716,860 or in German patent publication 195 37 163.
In both syringe types, the closure system is typically releasably attached via backcuts or projections on the syringe body.
This type of attachment is very complex during manufacture. The type of attachment makes it necessary to operate with high precision with respect to the syringe body as well as the closure arrangement in order to ensure that, for example, the closure arrangement does not drop off or loosen because of the thermal expansion of the entire system, for example, because of a sterilization of the filled and closed syringe such as in an autoclave at 121xc2x0 C./20 minutes in accordance with the requirements of medical standards or that this leads to a closure arrangement which is microbiologically untight.
The following is also considered. Often, the requirement is present that it must be ensured that the disposable syringe cannot be used again. This leads to the necessity of ensuring that a closure system, once opened, cannot be returned to its original state.
Such xe2x80x9coriginal closuresxe2x80x9d (manufacturer""s seal) are, for example, known for the syringe type having an integrated needle from German patent publication 297 08 314 and for the syringe type having a connecting cone from European patent publications 0,917,882 and 0,830,868 (in addition to the already mentioned publications, German patent publication 195 37 163 and European patent publication 0,716,860). 
In all these known cases, as with the closure arrangements without an original seal, the external stiff plastic cap is mechanically fixed on the syringe body by backcuts and/or projections and has the disadvantageous consequences already mentioned initially herein.
It is an object of the invention to provide a simple and reliable closure arrangement for a prefillable disposable syringe made of plastic with and without an integrated needle which requires no back cuts or projections for mechanically fixing the closure arrangement on the syringe body and which is configured as an original closure.
The closure arrangement of the invention is for a prefillable disposable syringe made of plastic. The disposable syringe includes a syringe body having a discharge end and an injection needle having a needle tip and the injection needle is fixedly connected to the discharge end. The closure arrangement includes: an outer stiff plastic cap made of hard elastic material; the plastic cap defining an interior and being seated on the syringe body so as to encase the injection needle; a sealing lining disposed in the interior at least in the region of the needle tip and the sealing lining being made of a soft elastic material; the plastic cap and the syringe body conjointly defining a joining interface; and, separable joining means formed at the joining interface to connect the plastic cap to the syringe body so as to permit a user to separate the plastic cap from the syringe body.
In another embodiment, the closure arrangement includes: a connecting cone being formed on the discharge end; an elastomeric closure cap seated on the connecting cone; a stiff plastic cap covering the closure cap and the plastic cap and the syringe body conjointly defining a joining interface; and, separable joining means formed at the joining interface to connect the plastic cap to the syringe body so as to permit a user to separate the plastic cap from the syringe body.
The measures in accordance with the invention provide a simple but reliable connection via the welding or gluing operations, which are relatively simple to carry out in a manufacturing context. This reliable connection fixes the closure arrangement even when there is increased internal pressure in the vessel which occurs during autoclaving and thereby guarantees the seal tightness and especially the microbiological seal tightness and requires no backcuts and/or projections because of the fixing of planar surfaces.
Once the closure arrangement is opened by breaking though the separation location, the closure arrangement cannot again be returned to its original condition at least not with the means available to a user. Desired separation locations in the context of original seals are known from the publications cited initially herein.